Mechanical fuel shut-off system for a gas turbine

ABSTRACT

The invention concerns a shut-off valve member which can be moved by spring force into a position in which it interrupts the fuel line to the gas turbine. The shut-off valve member is held by a likewise pre-tensioned scissor-type mechanism in the position in which it opens the fuel line. If a faulty gas turbine component acts on the scissor-type mechanism, the shut-off valve member is released and moves abruptly into the position in which it interrupts the fuel supply. The gas turbine is thus switched off safely and reliably in the event of failure of a component, for example the turbine shaft.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a mechanical shut-off system in the fuel supplysystem of a gas turbine, having a shut-off valve body which, by means ofa spring, can be brought into a position interrupting a fuel line. Thesystem further has a mechanism which, in the normal operation of the gasturbine holds the shut-off valve body in a position releasing the fuelline and releases the shut-off valve body in the event of damage orbreakage of a structural element of the gas turbine. Such a mechanicallyoperated shut-off system which, for example, in the event of a breakageof a gas turbine shaft, abruptly interrupts the fuel supply system ofthe gas turbine, according to existing regulations, must be provided,for example, on a flight gas turbine, and is known from British PatentDocument GB-A-903 945 or U.S. Patent Document U.S. Pat. No. 3,050,939.

It is sometimes difficult to arrange these known shut-off systems, suchthat on a gas turbine, in the event of all possible damage cases orbreaks on important structural components of the gas turbine, a secureinterruption of the fuel supply takes place. The reason is that thecorresponding mechanism which releases the shut-off valve body in theevent of damage must definitely be impacted by the broken or damagedcomponent.

In view of the above, it is an object of the present invention toprovide a simple and reliable mechanical shut-off system. For achievingthis object, it is provided that the mechanism is constructed as ashear-type (scissor-type) mechanism acted upon by a spring, whichshear-type mechanism comprises an arm which is constructed such that, inthe event of damage or a break of a structural element of the gasturbine, it is acted upon so that it releases the shut-off valve body.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a schematic diagram of the mechanical shut-off systemaccording to the present invention.

DETAILED DESCRIPTION OF THE DRAWING

Referring to the schematic diagram, reference number 1 indicates ahousing in which a shut-off valve body 3 is guided in a longitudinallyslidable manner according to the direction of the arrow 2. If thisshut-off valve body 3 is in the illustrated position, a fuel line 4which penetrates the housing 1 transversely to the direction of thearrow 2 is not interrupted whereas this fuel line 4 is interrupted whenthe shut-off valve body 3 has moved to the right and comes to rest withits center section 3' in the area of this fuel line 4-in this position,the shut-off valve body 3 is illustrated by thin lines. In the positionof the shut-off valve body 3 illustrated by thick lines, fuel cantherefore reach, by way of the fuel line 4, the combustion chamber ofthe gas turbine, which is not shown. In contrast, if the shut-off valvebody 3 comes to rest farther on the right in the area of the fuel line4, the fuel supply to the combustion chamber of the gas turbine isinterrupted because the fuel line 4 will then be shut off.

By way of a traction rope 5' (cable) as well as an adjoining threadedrod 5, a pressure spring 6 (which is also supported on the housing 1) isapplied to the shut-off valve body 3 and seeks to move the shut-offvalve body 3 toward the right according to the direction of the arrow 2.In this case, the force of the pressure spring 6 can be preadjusted byusing an adjusting nut 7 interacting with the threaded rod 5 so that,when there are no counterforces, the shut-off valve body 3 is broughtinto the position shutting-off/blocking the fuel line 4.

While the described pressure spring 6 is applied to the right side ofthe shut-off valve body 3, a shear-type mechanism is applied to the leftside of the shut-off valve body 3. As a whole, the shear-type mechanismhas the reference number 8. At first, the shear-type mechanism holds theshut-off valve body 3 in the position illustrated by thick lines. Withrespect to details, this shear-type mechanism 8 is formed by two arms9a, 9b, in which case arm 9a is linked in a stationary manner and arm 9bcan be swivelled about a hinge point 10. In this case, the swivellablearm 9b is prestressed by a tension spring 11 such that the two arms 9a,9b are capable of holding a connection element 12 by means of their freeends. This connection element 12 is connected with the shut-off valvebody 3 by means of a traction rope or cable 13 which is guided by way ofa deflection pulley 14.

In the prestressed illustrated position, in which the fuel line 4 is notinterrupted, the shut-off valve body 3 is therefore held by theshear-type mechanism 8. If now a structural element of the gas turbinewhich is situated close to the shears-type mechanism 8 (and which is notshown) suffers damage and is possibly even broken, this structuralelement will, for example, impact according to the arrow 15 on theswivellable arm 9b of the shears-type mechanism 8. This impact impulseof the destroyed structural element of the gas turbine is larger thanthe force of the tension spring 11 so that the shear-type mechanismopens and, in the process, the connection element 12 is released. Thisallows the pressure spring 6 to displace the shut-off valve body 3, asdescribed above, into the position in the direction of the arrow 2 whichinterrupts the fuel line 4. In the event of the occurrence of damage,the fuel supply of the gas turbine can be abruptly and reliablyinterrupted in this manner. In the event of damage, the shear-typemechanism can naturally also be triggered in a different manner butalways, in the widest sense by the damaged structural element, forexample, the turbine shaft. Naturally, the present invention wasexplained only by means of a schematic diagram, constructive details mayin this case definitely be designed to differ from the illustratedembodiment without leaving the content of the claims.

I claim:
 1. A mechanical shut-off system for a fuel supply system of agas turbine, comprising:a shut-off valve body which is brought into aposition interrupting a fuel line of the fuel supply system via aspring; a mechanism which, in a normal operation of the gas turbineholds said shut-off valve body in a position opening said fuel line andwhich releases said shut-off valve body in an event of damage orbreakage of a structural element of the gas turbine; wherein saidmechanism comprises a shear-type mechanism and a second spring whichacts upon said shear-type mechanism, said shear-type mechanismcomprising a first arm constructed such that it is acted upon so as torelease said shut-off valve body in the event of damage or breakage ofthe structural element of the gas turbine.
 2. The mechanical shut-offsystem according to claim 1, further comprising:a connection element ofsaid shut-off valve body; a traction rope connecting said connectionelement with said shut-off valve body; threaded rod having an adjustingnut which applies said first spring constructed as a pressure spring tosaid shut-off valve body; wherein said shear-type mechanism furthercomprises a second arm which is stationarily disposed, said first armbeing rotated about a hinge point, said first and second arms beingapplied to said connection element; further wherein said second springis provided on a side of said hinge point situated opposite saidconnection element and is constructed as a tension spring applied to therotatable first arm of the shear-type mechanism such that, in an eventof breakage of the structural element of the gas turbine, saidstructural element actuates said rotatable first arm against a directionof the tension spring force to release said connection element.